Tirmidhi

1؎ :
The meaning is that whatever pains and hardships befall a believer in this world, Allah, by His grace, makes them an expiation for his sins.
But this is only in the case when the believer exercises patience.
And if, instead of patience, he displays impatience and begins to lament over fate, then not only will he be deprived of this reward,
but there is also the danger that he may have to bear the burden of further sins.

Hadith Commentary:
(1)
The reason for the occurrence of these hadiths is that the Messenger of Allah (sallallahu alayhi wa sallam) suddenly experienced pain at night, so due to the intensity of the pain, he began to turn from side to side on the bed.
Aisha (radi Allahu anha) said:
"O Messenger of Allah! If any one of us were to do this, you would become displeased."
At that time, he said:
"Righteous people are afflicted with trials and hardships."
(Musnad Ahmad: 159/6, 160)
In a narration of Ibn Hibban, it is mentioned that due to the pain, Allah, the Exalted, wipes away sins and also raises ranks.
(Sahih Ibn Hibban bi Tartib Ibn Balban: 167/7, No. 2906)

(2)
Its meaning is that pain becomes a cause for both the removal of punishment and the attainment of reward.
In any case, if a person experiences pain, it becomes an expiation for his sins, and if he endures it considering it as the decree of Allah, the Exalted, then it also becomes a means of attaining reward.
(Fath al-Bari: 131/10)

Hadith Commentary: Benefits and Issues: The reason for the laughter of Aisha radi Allahu anha is that she indicated by gesture to express that she herself was the person involved in the incident and an eyewitness, or she laughed remembering that there was once such a time and that she had received so much love and affection from the Prophet sallallahu alayhi wa sallam, or she laughed because, for the sake of explaining a legal issue, it became necessary to mention such matters which, under normal circumstances, are not preferred to be expressed. According to Imam Ahmad rahimahullah, Ishaq rahimahullah, and Imam Dawud az-Zahiri rahimahullah, it is permissible for a fasting person to kiss without distinction (for everyone). According to Imam Malik rahimahullah, it is disliked (makruh) for everyone. According to Imam Abu Hanifah rahimahullah and Imam Shafi'i rahimahullah, it is disliked for the young and permissible for the elderly. This is one opinion of Imam Malik rahimahullah, and another opinion is that it is permissible in a voluntary (nafl) fast but not in an obligatory (fard) fast. If ejaculation occurs, then by consensus the fast will be invalidated.

In the case of madhiy (pre-seminal fluid), according to the Hanafis and Shafi'is, the fast will remain valid, and according to Imam Malik rahimahullah, the fast must be completed and a make-up (qada) will be required. According to Imam Ahmad, one should break the fast and then make it up, but the correct view is that whether one is young or old, whether the fast is obligatory or voluntary, if one can control one's desires and emotions, then it is permissible; if there is a fear of losing control, then it is not permissible.